The curtain airbag is located in the vehicle at the upper edge of the inner side structure of the vehicle and, in the event of an accident, is inflated in such a way that in the inflated state it covers the inner side structure of the vehicle and thereby prevents the occupant from directly hitting the same and sustaining severe injuries.
For the protection of the occupant, an airbag, which is designed as most often a round bag and in the inflated state covers the steering wheel, is further provided in the steering wheel of the vehicle as well. As the steering wheel naturally is arranged to perform a rotational movement, with a steering wheel hub not being fixed the airbag as well performs this rotational movement, so that the airbag itself needs to be designed to be symmetric and in particular to be round, in order that it can fulfill its protective function independent of the position of the steering wheel.
Thus, in the event of an accident, during the occurring forward movement the occupant generally is protected by the side curtain airbag and the airbag in the steering wheel.
In tests it has turned out that in the event of a frontal impact with a small overlap only, for example of 10-25% of the front end of the vehicle, the A-pillar already at low impelling forces is dislocated very far into the passenger compartment. Furthermore, the dashboard of the vehicle is dislocated from its side edge obliquely to the center and the lower part of the A-pillar is intruding into the compartment of the vehicle, so that an enlarged gap between the side edge of the dashboard and the inner side structure of the vehicle is generated. Owing to the impact direction the occupant further is accelerated directly in the direction of the gap existent between the curtain airbag and the airbag of the steering wheel, so that owing to the non-existent connection of the airbags the occupant may hit the A-pillar moving in or from above may hit the side door frame through the airbags, or the occupant slides off the frontal airbag into the gap.
For the above-mentioned reasons, an enhanced risk of injury for the occupant even results from accidents with low impelling forces and a small lateral overlap.